Apparatus for preserving delicate food products

ABSTRACT

Delicate food products having substances that become volatile when subjected to sterilization heat can be preserved in flexible containers without loss of aroma or flavor by expelling air at room temperature from the food product and container, then sealing the container and sterilizing the product therein. Each container is filled with a food product and has an opening through which gases can be expelled while preventing liquid from entering. These containers are advanced by a conveyor through a liquid filled leg in an enclosed housing towards a vacuum chamber and, as pressure decreases outside the container, higher pressure gases within the container are expelled through the container opening. Hydrostatic pressure of the liquid within the leg prevents the container from swelling up in balloon fashion and, as the container moves towards the vacuum, pressure outside the container gradually decreases. By the time the container reaches the vacuum, substantially all air is expelled from the container. Processing apparatus includes a vacuum chamber with a liquid filled leg through which a conveyor is adapted to travel, a sealer within the vacuum chamber for sealing containers passing through, and a hydrostatic cooker through which the conveyor passes for sterilizing food products in the sealed containers.

United States Patent Wilson APPARATUS FOR PRESERVING DELICATE FOODPRODUCTS Donald C. Wilson, San .lose, Calif. [73] Assignee: FMCCorporation, San lose, Calif.

[22] Filed: May 3, 1971 [21] Appl. No.: 139,648

[72] Inventor:

[56] References Cited UNITED STATES PATENTS 1,419,139 6/1922 Hunter..99/362 1 ,843,522 2/1932 Sprague ..99/272 2,660,512 1 1/1953 Webster..99/362 2,968,232 l/196l Carvallo ..99/360 3,407,721 10/1968 Carvallo..99/249 Primary ExaminerRobert W. Jenkins Attorney-F. W. Anderson, C.E. Tripp and J. W. Edwards Oct. 24, 1972 7] ABSTRACT.

Delicate food products having substances that become volatile whensubjected to sterilization heat can be preserved in flexible containerswithout loss of aroma or flavor by expelling air at room temperaturefrom the food product and container, then sealing the container andsterilizing the product therein. Each container is filled with a foodproduct and has an opening through which gases can be expelled whilepreventing liquid from entering. These containers are advanced by aconveyor through a liquid filled leg in an enclosed housing towards avacuum chamber and, as pressure decreases outside the container, higherpressure gases within the container are expelled through the containeropening. Hydrostatic pressure of the liquid within the leg prevents thecontainer from swelling up in balloon fashion and, as the containermoves towards the vacuum, pressure outside the container graduallydecreases. By the time the container reaches the vacuum, substantiallyall air is expelled from the container. Processing apparatus includes avacuum chamber with a liquid filled leg through which a conveyor isadapted to travel, a sealer within the vacuum chamber for sealingcontainers passing through, and a hydrostatic cooker through which theconveyor passes for sterilizing food products in the sealed containers.

7 Claims, 5 Drawing Figures PATENTEDUBT 24 m2 SHEET 2 OF 2 FIE|' 2TENSION APPARATUS FOR PRESERVING DELICATE FOOD PRODUCTS CROSS REFERENCETO RELATED PATENT The method and apparatus of the present invention is amodification of the method and apparatus disclosed in U.S. Pat. No.,3,501,318 by the same inventor and assigned to the same assignee. Thedisclosure of that patent is incorporated herein by reference andparticular attention will be directed to specific portions thereof inthe following description.

BACKGROUND OF THE INVENTION 1. Field of the Invention This inventionrelates to an improved method and apparatus for preserving delicate foodproducts and beverages without loss of flavor or aroma. Moreparticularly, the method concerns expelling air at normal temperaturefrom flexible containers filled with a food product, sealing thecontainers, and sterilizing the product therein. The apparatus forcarrying out this method includes the combination of an exhauster, asealer, and a hydrostatic cooker.

2. Description of the Prior Art When preserving food products, it isnecessary to expell headspace air, interstitial air within a product andair dissolved in the product or packaging medium before containers aresealed to prevent subsequent oxidation of the product. Air purgingmethods disclosed in US. Pat. No. 3,501,318 include the step ofsterilizing a food product by heating in an unsealed flexible container.The sterilization heat causes the formation of aqueous vapors within thecontainer and these vapors together with other gases are expelledtherefrom through a one-way valve. A problem is encountered whenpreserving delicate food products in this manner. Some food productshave substances that become volatile when heated to sterilizationtemperature and the flavor or aroma is lost with vapors and gases thatare expelled.

Apparatus for expelling air at room temperatures from a food product andcontainer must also be suitable for continuous operation with otherprocessing equipment such as a sealer for sealing the container and ahydrostatic cooker for sterilizing the product therein. Running aconveyor continuously through a vacuum chamber presents problems insealing the vacuum chamber and maintaining the desired vacuum.

SUMMARY OF THE INVENTION Delicate foods and beverages can be preservedwithin flexible containers without loss of flavor or aroma by expellingair therefrom at room temperature or temperatures below roomtemperature, then sealing the containers and sterilizing the producttherein. The containers have an opening that forms a one-way valvethrough which air can be expelled while preventing liquid from enteringtherein. A conveyor advances these containers through a liquid filledleg in an enclosed housing that forms a hydrostatic seal for a vacuumchamber. As pressure outside a container decreases, gases within thecontainer at higher pressure are expelled through the one-way valve. Bythe time the container reaches the vacuum chamber, substantially all ofthe gases are expelled and the container is sealed by a sealer locatedwithin the vacuum chamber. The conveyor then carries the sealedcontainer through a hydrostatic cooker for sterilizing the product whilepreserving volatile substances within the sealed container.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a diagrammatic verticalcentral section of an enclosed housing including an exhauster, sealerand hydrostatic cooker for practicing the present invention.

FIG. 2 is an enlarged plan illustrating a fragment of the conveyor and acarrier with container supporting clamps thereon.

DESCRIPTION OF THE PREFERRED EMBODIMENT As illustrated in FIG. 1, aprocessing apparatus 10 is provided to continuously expell air at roomtemperature from products filled in flexible containers or pouches 11(FIGS. 3-5), and to then seal the containers and sterilize the producttherein. The flexible containers are preferably made of a heat sealable,laminated film having an outer layer formed of a polyester resin film, acentral layer of thin aluminum, and an inner layer of polyethylene.Prior to being filled, the lower edge 12 and side edges 13 and 14 ofside walls 15 and 16 of the container are hermetically sealed byapplication of heat and pressure to provide a flat container having anunsealed or open upper end portion 17 which defines the mouth 18 (FIGS.3 and 4) of the container, a one-way valve 19 is formed in the mouth ofthe container as will be described hereinafter.

Processing apparatus 10 (FIG. 1) includes a housing 22 defined by abottom 23, end walls 24 and 25, side walls 26 (only one of which isshown), and a top 27 all of which are secured together in fluid tightrelationship I as by welding. A pair of baffles 28 and 29 depend fromthe top and extend between the side walls to define an auxiliary vacuumchamber 30 which is sealed by liquid within an inlet leg 31 and a secondleg 32.

Inlet leg 31 is formed between end wall 24 and baffle 28 and continuesbetween baffle 28 and a baffle 38, extending upward from the bottom ofthe housing, to provide communication with auxiliary vacuum chamber 30.The inlet leg has an effective hydrostatic height h indicated in thedrawing, representing the difference between the levels of liquidtherein which seals the auxiliary vacuum chamber from the atmosphere. Afluid inlet 34 and a valved drain conduit 35 are provided to maintain adesired amount of liquid within the liquid leg. Second leg 32 is formedbetween bafile 33 and baffle 29 and continues upwardly between baffle 29and a baffle 37 that depends from top 27. The second leg has aneffective hydrostatic height h as indicated in the drawing.

fies 29 and 37 (coextensive with the terminal portion of the second leg32) and continues between baffle 37 and a baffle 41 that projectsupwardly from bottom 23. The

third leg has an effective hydrostatic height 11 as indicated in thedrawing. A fluid inlet 42 and a valved drain conduit 43 are provided tomaintain a desired amount of liquid in both the second and third legsand thereby adjust the level of the intermediate vacuum in the auxiliaryvacuum chamber 30.

A second auxiliary vacuum chamber 45 is formed between baffle 37 and abaffle 46 that depends from top 27. This vacuum chamber is sealed byliquid in both third leg 40 and a fourth leg 47, and the amount ofvacuum therein is created by the vacuum in the chamber 38 which causesthe level of the liquid in the fourth leg to drop. The fourth leg isformed between baffles 41 and 46 and continues between baffle 46 and abaffle 48 extending upward from bottom 23. The fourth leg has aneffective hydrostatic height h., and liquid is supplied thereto throughan inlet 50 and removed therefrom through a valved drain conduit 51.

A baffle 53 depends from top 27 and a chamber 54 is formed betweenbaffles 46 and 53. Pressure within this chamber is normally atatmospheric level. A fifth leg 55 having an effective hydrostatic heighth is formed between baffles 48 and 53 and continues between baffle 53and a baffle 56 that projects upward from bottom 23. Liquid is suppliedto the fifth leg through an inlet 57 and removed through a valved drainconduit 58.

A baffle 59 depends from top 27 and an auxiliary pressure chamber 60 isformed between baffles 53 and 59. Steam under pressure is directed intothe auxiliary pressure chamber through a valved conduit 61. This chamberis sealed by liquid in fifth leg 55 and a sixth leg 62, formed betweenbaffles 56 and 59. The sixth leg has an effective hydrostatic height hand continues upward between baffle 59 and a baffle 63 depending fromtop A sterilizing chamber 64, formed between baffles 59 and 63, issealed by liquid in sixth leg 62 and a seventh leg 65. Steam underpressure is directed into the sterilizing chamber through a valvedconduit 66. The

seventh leg is formed between baffles 59 and 63 and continues upwardbetween baffle 63 and a baffle 67 projecting upward from bottom 23. Theseventh leg has an effective hydrostatic height 11,. Liquid is fed toboth the sixth and seventh legs, which have a coextensive portiondefining the bottom of the sterilizing chamber 64, from an inlet 68 andremoved therefrom through a valved drain conduit 69.

An auxiliary pressure chamber 70 is formed between baffle 63 and abaffle 71 that depends from top 27. Pressure within this chamber iscontrolled by a valved conduit 72 supplying compressed air thereto andthe chamber is sealed by liquid in seventh leg 65 and an outlet leg 73.The outlet leg is formed between baffles 67 and 71 and continues upwardbetween baffle 71 and end wall 25, having an effective hydrostaticheight h Liquid is fed to the outlet leg through 'an inlet 74 andremoved therefrom through a valved drain conduit 75.

The water in fifth leg 55 and sixth leg 62 is thermostaticallycontrolled to provide increasing water temperatures in the transfer legsfrom approximate room temperature in chamber 54 to a sterilizingtemperature in the range of 160250 F for most food products to beprocessed in sterilizing chamber 64. it will be understood that thesterilizing chamber and the hydrostatic legs sealing the chamber areformed by a regular hydrostatic cooker unit having the normaltemperature-pressure range capabilities. Seventh leg 65 and outlet leg73 are thermostatically controlled to provide decreasing watertemperatures in the transfer legs from the sterilizing chamber to anysuitable temperature below the boiling point of the liquid in thecontainer at atmospheric pressure.

And endless conveyor 77 is provided for carrying the pouches 11 throughthe various aforedescribed chambers which conveyor comprises a pair ofparallel endless chains, and details of the construction of the conveyorare disclosed in US. Pat. No. 3,501,3l8 at column 4, lines 46-69, withreference to FIGS. 2, 3 and 4 of that patent. As shown in the drawingsof the present application, the endless conveyor is trained aboutsuccessively arranged sprockets 78, 79, 80, 81, 82, 83, 84, 85, 86, 87,88, 89, 90, 91, 92, 93, 94, and 96 which are keyed to shafts 97, 98, 99,100, 101, 102, 103, 104, 105, 106, 107, 108, 109, 110, 111-, 112, 113,114 and 115, respectively. A motor 116 is operatively connected to shaftby a drive chain 117 and continuously drives conveyor 77 in thedirection indicated in FIG. 1.

Endless conveyor 77 includes a plurality of uniformly spaced containercarriers 118 (FIGS. 2, 3 and 4) for supporting flexible containers 11.While only a portion of one container carrier is shown, it will beunderstood that each container carrier can support a row of flexiblecontainers as shown in U.S. Pat. No. 3,501,3l8. Each carrier comprises achannel 119 with projecting arms 120 welded to opposite ends thereof. Ahook is provided on the upper end of each arm for attachment to the pairof parallel endless chains which form the v endless conveyor. Alternatepivot pins 121 of the endless chains are axially aligned and projectinwardly from the chains for supporting the hooked arms of the containercarriers, while enlarged heads 122 are provided on the inner ends of thepivot pins to retain the hooked arms thereon.

Each flexible container 11 is connected to one of the carriers 118 by aclamp 124 that grips the lower edge 12 to prevent flotation of thecontainer when submerged and by clamps 125 and 126 which grip the sideedges 13 and 14 of the container adjacent mouth 18. Clamps 125 and 126are mounted near the upper ends of bars 127 and 128 that are mounted onthe channel 119 and are resiliently stressed to apply a tensioning forceacross mouth 18 of the container to provide a one-way valve 19 (FIG. 4).A tensioning force of between about /2 to about 1% pounds has been foundto be desirable when a laminated flexible container that is about5inches wide is being processed.

As best shown in FIG. 2, clamps 124, 125 and 126 each have a body 130fastened to channel 119, bar 127 or bar 128, respectively, as bybolting. A clamping jaw 131 is pivotally connected to the body by a pin132 and is urged into gripping engagement with container 11 by acompression spring 133 fitted between the body and an enlarged head 134on a jaw actuating lever 135. The jaw actuating lever includes a plunger136 which is slidably received in an opening 137 within the body and hasan upper pivot portion 138 bent at right angles to the remainder of theplunger which extends through a hole injaw 131.

When it is desired to clamp a filled flexible container 11 to one of thecarriers 118, plungers 13.6 of three associated clamps 124, 125 and 126are depressed, opening jaws 131 thereof and permitting the appropriateedges of the flexible container to be placed between the jaws and thebodies 130 of the clamps. The plungers are then released permittingsprings 133 to urge the jaws into firm gripping engagement with thecontainer. The resilience of bars 127 and 128 provides the necessarytensioning forces across mouth 18 of the container, as indicated in FIG.3, to provide a one-way valve that allows gases to be discharged fromthe container but prevents fluids from entering therein.

A sealing mechanism 140 (FIGS. 1 and 4) is located within vacuum chamber38 for sealing each container 11 passing through the vacuum chamber. Thesealing mechanism includes an electrically heated sealing bar 141 and acooperating pressure resisting anvil 142. The sealing bar is preferablyheated to about 320 F, and, during the sealing operation, the sealingbar and anvil pivot together, as indicated in phantom lines in FIG. 4,on opposite sides of container mouth 18 which is subjected to a sealingpressure of about 150 p.s.i. for about W; seconds. Details of theconstruction of the sealing mechanism are disclosed in US. Pat. No.3,501,318at column 5, line 43 through column 6, line 18, with referenceto FIGS. 5 and 6 of that patent.

In carrying out the process of the present invention, filled flexiblecontainers 11 with their upper ends unsealed are clamped to a carrier118 in a manner tensioning the unsealed upper ends to form one-wayvalves, and the carrier is then attached to the continuously drivenconveyor 77 (at the upper left hand corner of the conveyor as shown inFIG. 1) for movement through apparatus 10 in the direction indicated bythe arrows in FIG. 1.

When a flexible container 11 enters the liquid within inlet leg 31,hydrostatic pressure expells head-space air from the container. As thecontainer advances upward between baffles 28 and 33, through auxiliaryvacuum chamber 30 and second leg 32, interstitial air and dissolved airwithin the product is expelled due to the fact that pressure outside thecontainer is less than atmospheric level. Hydrostatic pressure preventsthe container from swelling like a balloon and the pressure dropsprogressively as the container advances. When the container reaches mainvacuum chamber 38, substantially all air should be expelled therefromwithout rupturing or foaming the product. In order to prevent thedesirable aromas and flavors from boiling off as the pressure is reducedin the vacuum chambers, it may be necessary to reduce the temperature inthe vacuum chambers to temperatures below room temperature for someproducts. Obviously, the temperatures cannot be lower than the freezingpoint of the liquid in the hydrostaticlegs although liquids other thanwater and with a lower freezing point might be used in the legs if itshould prove necessary to maintain low temperatures in order to preventthe evaporation of the desirable aromas in the product. The reducedtemperatures in the first, second and third legs can be achieved byconventional refrigerating coils.

The open mouth 18 of container 11 is sealed within vacuum chamber 38by'sealing mechanism 140. Sealed containers then advance through thirdleg 40. and fourth leg 47 as the external pressure builds back up toatmospheric level.

As the sealed containers l1 continuethrough fifth leg 55, auxiliarypressure chamber and sixth leg 62,

"and outlet leg 73. Processed containers are removed from conveyor 77and replaced by filled but unsealed containers to be processed. I

Auxiliary vacuum chambers 30 and 45 are provided for maintaining adesired high vacuum within vacuum chamber 38, while limiting the heightof the hydrostatic legs. It will be seen that the pressure within vacuumchamber 38 equals atmospheric pressure minus the head represented by h hA single leg of a height equal to h k or h;, It, might be too tall forconvenience but would function in the same manner. Thus, it will be seenthat the legs sealing the vacuum chamber can be divided into any desirednumber each having a desired hydrostatic height which heights arecombined to produce the required transfer head.

Conveyor 77 could enter and exit vacuum chamber 38 through the same legsbut for illustration simplification, legs 31 and 32 are shown for entrywhile legs 40 and 47 are provided for exit.

Although the best mode contemplated for carrying out the presentinvention has been herein shown and described, it will be apparent thatmodification and variation may be made without departing from what isregarded to be the subject matter of the invention.

I claim:

1. Processing apparatus comprising means defining a vacuum chamber,means for reducing the pressure within said chamber to a predeterminedsub-atmospheric level, means defining a liquid filled leg incommunication with the vacuum chamber and extending downward therefrom;said leg having an effective vertical height of liquid therein to form apressure seal balancing the less than atmospheric pressure within thevacuum chamber against the higher external pressure at the end of theliquid filled leg farthest from the vacuum chamber; and a conveyoradapted to travel continuously through said leg and vacuum chamber foradvancing articles to be processed therein.

2. The processing apparatus described in claim 1 wherein said article tobe processed include food products in partially filled flexiblecontainers each having an opening therein, means for mounting saidcontainers upon said conveyor so that liquid is prevented said sealingmeans applies heat and pressure to the con-" tainers for sealing theopenings of same.

5. The processing apparatus described in claim 3 including heattreatment apparatus through which said conveyor is adapted to travel forsterilizing said food products in the flexible containers after thecontainer openings have been sealed.

6. The processing apparatus described in claim 5 wherein said heattreatment apparatus is a hydrostatic cooker having means defining avertically extending water filled inlet leg, means defining a verticallyextending water containing outlet leg, and means defining a steam filledchamber communicating with said inlet I and outlet legs.

7. The processing apparatus described in claim 1 including meansdefining an auxiliary vacuum chamber connected to said liquid filled legat said end farthest from the vacuum chamber, means for reducing thepressure within said auxiliary vacuum chamber to a predeterminedsub-atmospheric level higher than the pressure in said vacuum chamber,and means defining another vertically extending liquid filled leg incommunication with the auxiliary vacuum chamber and having an efi'ectivevertical height sufficient for the liquid therein to form a pressureseal balancing the less than atmospheric pressure within the auxiliaryvacuum chamber against the external pressure at the opposite end of theleg whereby the pressure differential over both of said legs iscumulative, said conveyor being adapted to travel through both legs andvacuum chambers for advancing articles to be processed therein.

1. Processing apparatus comprising means defining a vacuum chamber,means for reducing the pressure within said chamber to a predeterminedsub-atmospheric level, means defining a liquid filled leg incommunication with the vacuum chamber and extending downward therefrom;said leg having an effective vertical height of liquid therein to form apressure seal balancing the less than atmospheric pressure within thevacuum chamber against the higher external pressure at the end of theliquid filled leg farthest from the vacuum chamber; and a conveyoradapted to travel continuously through said leg and vacuum chamber foradvancing articles to be processed therein.
 2. The processing apparatusdescribed in claim 1 wherein said article to be processed include foodproducts in partially filled flexible containers each having an openingtherein, means for mounting said containers upon said conveyor so thatliquid is prevented from entering therein while gases are permitted tobe expelled therefrom; said conveyor being arranged to advancecontainers through the liquid filled leg towards the less thenatmospheric pressure within the vacuum chamber, whereupon higherpressure gases within the containers are expelled through the opening asthe liquid pressure decreases.
 3. The processing apparatus described inclaim 2 including means located within the vacuum chamber for sealingthe container openings as the containers are continuously advancedthrough the chamber.
 4. The processing apparatus described in claim 3wherein said flexible containers are heat sealable and said sealingmeans applies heat and pressure to the containers for sealing theopenings of same.
 5. The processing apparatus described in claim 3including heat treatment apparatus through which said conveyor isadapted to travel for sterilizing said food products in the flexiblecontainers after the container openings have been sealed.
 6. Theprocessing apparatus described in claim 5 wherein said heat treatmentapparatus is a hydrostatic cooker having means defining a verticallyextending water filled inlet leg, means defining a vertically extendingwater containing outlet leg, and means defining a steam filled chambercommunicating with said inlet and outlet legs.
 7. The processingapparatus described in claim 1 including means defining an auxiliaryvacuum chamber connected to said liquid filled leg at said end farthestfrom the vacuum chamber, means for reducing the pressure within saidauxiliary vacuum chamber to a predetermined sub-atmospheric level higherthan the pressure in said vacuum chamber, and means defining anothervertically extending liquid filled leg in communication with theauxiliary vacuum chamber and having an effective vertical heightsufficient for the liquid therein to form a pressure seal balancing theless than atmospheric pressure within the auxiliary vacuum chamberagainst the external pressure at the opposite end of the leg whereby thepressure differential over both of said legs is cumulative, saidconveyor being adapted to travel through both legs and vacuum chambersfor advancing articles to be processed therein.